U.S. Pat. No. 4,503,067 describes a compound, which is known as carvedilol. This compound is a novel multiple action drug useful in the treatment of mild to moderate hypertension. Carvedilol is known to be both a competitive non-selective β-adrenoceptor antagonist and a vasodilator. The vasodilatory actions of carvedilol result primarily from α1-adrenoceptor blockade, whereas the β-adrenoceptor blocking activity of the drug prevents reflex tachycardia when used in the treatment of hypertension. These multiple actions of carvedilol are responsible for the antihypertensive efficacy of the drug. Also, carvedilol, as a consequence of its antioxidant action in attenuating oxygen free radical-initiated lipid peroxidation, is useful in organ protection, in particular, cardio protection. Additionally, carvedilol is useful in the treatment of congestive heart failure.
US patent application 2004/0234602 discloses use of stabilizing agents like antioxidants suitable for use also in situation where the active substance is subject to oxidation: acids (ascorbic acid, erythorbic acid, etidronic acid, gallic acid, hypophosphorous acid, nordihydroguairetic acid, propionic acid etc.), phenols (e.g. BHA, BHT, t-butyl hydroquinone, dodecyl gallate, octyl gallate, 1,3,5-trihydroxybenzene), organic and inorganic salts (calcium ascorbate, sodium ascorbate, sodium bisulphite, sodium metabisulfite, sodium sulfite, potassium bisulphite, potassium metabisulphite), esteres (calcium ascorbate, dilauryl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate), pyranon (maltol), and vitamin E (tocopherol, D-∝-tocopherol, DL-∝-tocopherol, tocopheryl acetate, d-∝-tocopheryl acetate, dl-∝-tocopheryl acetate.
A need exists in the art for methods to stabilize solid oral pharmaceutical dosage forms comprising carvedilol or a pharmaceutically acceptable salts thereof. These stabilized pharmaceutical dosage forms would allow for longer storage periods, and would allow the amount of components to remain constant over the storage period.